Manufacture and production of alkyl esters



Patented Feb. 9, 1926.

UNITED STATES PATENT OFFICE.-

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No Drawing.

To all whom it may concern:

Be it known that I, RUDOLF WIETZEL, citizen of the German Empire, residing at Ludwigshafen-on-the-Rhine, Germany, have invented new and useful Improvements in the Manufacture and Production. of Alkyl Esters, vof "which the following is a speci-. fication. 1

This invention relates to an im roved method of preparing alkyl esters. an more especially alkyl formates. Attempts have been made to produce such esters by the action of carbon monoxide on alcohols in the presence of sodium. alcoholate, at room temperature, or at temperatures in the neighborhood of 200' degrees centigrade, but the quantity of. ester-obtained was either very small or' place. K I have now found that alkyl formates can be obtained in a very short time :and with very good yield's'when carbon monoxide is causedto act on analcohol at all elevated pressure and in the presence of a metal alcoholate at a moderately elevated -temperature ranging between about degrees and 150 degrees centigrade,-the preferred range beinlg between 60 and 100 degrees centira e. e a The process according to my resentinvention is more fully illustrated y the following examples which are however only typical and may ing' from the scope of the invention.

Example 1.

A cylindrical steel vessel capable of withstanding pressure is sup lied with methanol,

litre in a dissolved state. The vessel'is then heated to 80 degrees centigrade and carbon monoxide forced in until a pressure of 200 atmospheres is reached which is maintained by, introducing additional carbon monoxide either continuously .or at intervals. It is preferred to introduce the carbon monoxide by pipes reaching into the liquid content, of the autoclave so as to cause the liquid to the pressure is atmospheres, about three quarters of the methyl alcohol are transformed into formate after 3 hours, while with 1000 atmospheres the conversion is suitable materials. the decomposition. failed to take,

be varied without departthe vessel areheated to de containing 10 grams 0 sodium metal per eevaporates'at 54 degrees centigra'deand repuene if an addition thereof had been made.

be stirred thereby. The reaction is complete after a few hours. For example when Application filed Kay 20, 1925. Serial No. 31,702.

' practically complete after a few minutes. 8

Theproduct which is ractically pure methyl formate can either be withdrawn by. a reduction valve at the bottom of the cyl-- inder or distilled off through av valve at the top thereof. The main portion of s0di=4 um alcoholate is left behind in. theautoclave in a solid'state. For starting a fresh operation, methanolis then filled into the cylinder with as much sodium methylate as Is necessary to compensate for losses, if 65 there by any. As a general rule, it is preferable to'purify the carbon monoxide from iron carbonyl, sulphur compounds and moisture and to protect the apparatus against an attack of carbon monoxide by employing While in the. absence of iron carbonyl the raw product can be obtained nearly colourless, by its presence it would beintensely.

coloured in consequence of undesirable secondary reactions and it would take u a certain amount of iron compound whic it would be' difiicult to separate.

Example Ethyl alcohol either .pure or denatured with toluene is distilled over'quicklime in order to remove water. The dehydrated alcohol is filled in a vessel capable of withstanding pressure and lined with brass, after 1.5 per cent of sodium metal "has been dissolved in the alcohol. The vessel is I then supplied with carbon monoxide under a pressure of 120 atmospheres in-the absence of other gases, whereupon the contents of centigrade. After 4 hours-the reaction product is withdrawn .and subjected to fractional distillation. About 90 per cent or more resents pure ethyl formate which may .prove of valuable use as a solvent.' The residue consistssof unaltered ethyl alcohol and tol- VVhat Iclaim'is: 1. The process 9f manufactui'ing alkyl formates which consists incau'sing carbon monoxid' to react on liquid alcohols in the presence of a metal alcoholate and at an elevated pressure, at temperatures ranging 1 formates wlncn consists in causing carbon monoxid to react on liquid alcohols in the presence of a metal alcoholate and at an elevated pressure, at temperatures ranging between about 30 and 150 degfiees'i ehtigrade and avoiding the presence of iron carbonyl.

3. .The process of manufacturing alkyl fol-mates which consists in causing carbon monoxid to react on liquid alcohols in the presence of a metal alcoholate and at an 1 In testimony whereof I have hereunto set 1 my hand.

RUDOLF VVIETZEL. 

